In modern construction it is common to provide ventilation of closed spaces to allow moisture and the like to be removed. For example, in many houses there is a space below the peak of the roof which is not finished, and is called an attic. To allow for moisture and the like to be removed from the space it is common to provide one or more ventilation holes into the attic space. To avoid problems with rain snow and the like getting in through such ventilation openings it is common to provide a cover or vent. Such vents are typically located below the eaves in the gable, and may be centered, for example below a peak in the roof.
Another trend in modern construction is to clad the exterior of a residential building with a durable low maintenance cladding material. Examples of this type of material are aluminum and vinyl siding. The siding is typically provided with alternating ridges and valleys and imitates the lapped appearance of the original wood type of siding. Of course aluminum and vinyl siding is also lapped, to prevent water running behind the siding and penetrating to the interior of the building, by being absorbed through the walls or the like.
Such cladding or siding is made by many different manufacturers and in many different styles and sizes. Openings in the siding, corresponding to the ventilation openings, for example in the gables, are necessary to allow for proper ventilation. To prevent water from entering the building, it is preferable to have the siding lap over top of the ventilation cover. However, such siding may be difficult to precisely trim by hand and there is typically a rough uneven edge left at the end adjacent to the opening. Therefore it is preferable to have a trim edge or ring on the ventilation cover to hide this rough edge.
Unfortunately, there is a problem when the trim cover overlies the siding. Due to the uneven nature of the outer surface of the siding, by reason of the alternating peaks and valleys, it can be difficult to form a good seal against the siding. Various attempts have been made to deal with this problem. For example, in Canadian patent 1,280,024 granted 1991/02/12 to Tapco Products Company, Inc. there is provided a two part plastic louver, which has an integral body, which covers the ventilation opening and has a peripheral attachment flange. A trim ring is attachable on the outside of the body. In use, the body is attached to the building wall, the siding is than laid up to the edge of the body, and the trim ring is placed on last to cover the rough edges of the siding. The trim ring and the body are provided with cooperating interengaging ribs to allow the trim ring to be positioned on the body at a number of different heights so in effect the trim ring can be closely positioned against the siding.
Due to the nature of the peaks and valleys of the siding, as previously noted, even though the trim ring of this prior device is closely positioned or pressed against the peaks of the siding, there are gaps associated with the valleys. This means that in practice the installer is required to caulk around the exterior of the trim ring to ensure a waterproof seal. This is a time consuming, awkward and messy job which is better avoided, if possible.
To overcome the problem of the gaps, it has also been proposed to provide a serrated edge on the trim ring. However, since each siding manufacturer makes different sizes of lap height, length and overlap in their siding, and since there is no telling where the ventilation opening is going to be located relative to the laps in the siding, a preformed serrated edge is not likely to fit. One prior art solution as shown in Canadian patent application 2,002,710 laid open 1991/05/10 in the name of Dean F. S. Carew is to make a mould of the exact profile of the siding to be covered and then form a custom fit trim ring. However, such custom fitting is simply too expensive and labour intensive to be practical on a mass production scale. Further even though this may make the sealing easier, it will still be necessary to seal the edge of the trim ring against water.
What is desired therefore is an exterior ventilation device which is simple to install and yet provides a good protection against water. Such a device should overcome the problems of the lapped cladding material without requiring an individual customization of either a serrated edge of the trim ring, or any post installation sealing or caulking.